Automatic synchronization of pitches in electronic musical instruments with magnetic recording-reproducing apparatus



United States Patent [72] inventor Yasuji Uchiyama [56] References Cited Hamakita-shi, Japan UNITED STATES PATENTS i211 P 754,348 2,558,432 6/1951 HalOSki 179/1002 1 FM 3,011,378 l2/l96l Hurvitz 84/1.02 [451 3,197,543 7/1965 Williams..... 84/1 .28 [7 3] Ass1gnee Nippon Gakki Seizo Kabushiln Keisha 3,257,493 6/1966 Hurv1tz 84/l .02 Ihmamatsu-shi, Shizuolta-ken, Japan [32 1 p i it Aug 29, 19 7 Pnmary Examiner-Warren E. Ray [33] Japan Altorney- Holman, Glascock, Downing & Seebold [3 I Nos. 42/73458 and 42/73459 AUTOMATIC SYNCHRONIZATION 0F "TCRES ABSTRACT: A reference tone signal is recorded in a specific IN ELECTRONIC MUSICAL INSTRUMENTS Wl'lll ING channel of a multlple-channel recorder-reproducer mcor MAGNET: RECORMNGREPRODUC porated within an electronic musical instrument simultane- APPARATUS ously with recording of music played on the instrument. Dur- 4 Chim" 2 Drawing Fits ing reproduction, this reference signal is also reproduced and [52] U.S.Cl. 84/l.02, automatically compared with the corresponding tone signal 84/] .03, 84/ 1.28, 179/ i002 directly from a tone generator of the instrument to produce a [5 l] Int. Cl. Gl0h U02; comparison output, which is used to accomplish automatic Gl lb 31/02 equalization of the pitches of the music being reproduced and [50] Field of Search those of the corresponding tones of the tone generators of the instrument.

PAIEIIIIzIIum-smm Y 3546354 FIG. I

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3 KEYS 7' EXPRESSION 4FILTFR AMPLIFIER 8 TONE 5TONE GENERATORS 2 SWITCHES QY I AMPLIFIER ib REPRODUCE sf ||m L2 I I I *7 d IOq f j REPRODUCE lzfq RECORD 5 [4 v. s DETECTORLb I40 IOb I RECORD Q RECORDER REPRODuCER I REPRODUCE ATTwf/JE v:

GENERATORS FILTER -K AMPLIFIER gAMPLIFIER \I.

AUTOMATIC SYNCI-IRONIZATION F PITCHES IN ELECTRONIC MUSICAL INSTRUMENTS WITH MAGNETIC RECORDING-REPRODUCING APPARATUS BACKGROUND OF THE INVENTION This invention relates generally to electronic musical instruments and magnetic sound recording and reproducing apparatuses (hereinafter referred to as recorder-reproduces") and more particularly to electronic musical instruments having recorder-reproducers incorporated therein in a built-in manner.

More specifically, the invention concerns automatic equalization or synchronization of pitches in electronic musical instruments of the above stated character, that is, automatic synchronization whereby-aberrations or deviations of pitches of reproduced tones due to causes such as elongation of the recording tape at the time of reproduction and fluctuation in the speed of the tape drive motor are compensated for to cause the pitch of each reproduced tone and the pitch of the corresponding tone produced by a tone generator of the musical instrument to be equal.

In instances such as that when a recorder'reproducer is used in combination with an electronic musical instrument, and music generated by the electronic musical instrument is recorded on a recording tape and is subsequently reproduced therefrom, or when a previously recorded tape is used to reproduce music recorded thereon for purposes such as practice in playing the electronic musical instrument, the pitches of the reproduced tones tend to deviate from the pitches of the corresponding tones produced by the tone generators of the instrument.

This pitch deviation is due to causes such as deformation of the recording tape, fluctuation of the speed of the tape drive motor, and fluctuation of the tone generator of the electronic musical instrument itselfl'Consequently, when the musical instrument is played simultaneously with reproduction of a recorded musical composition, unmusical or discordant superimposed tones and chords .tend to be produced. This pitch deviation has heretofore been a major difficulty accompanying electronic musical instruments with built-in recorderreproducers.

SUMMARY OF THE INVENTION and one signal within the same tone generator as a reference signal at the time of recording, comparing this reference signal at the time of reproduction with the corresponding tone generator signal of the instrument at the time of reproduction to produce a comparison output, and apply this output to the motive power means of the recorder reproducer thereby to control the speed thereof and to obtain reproduced tone signals of the same pitches as the corresponding pitches of the musical instrument played at the time of reproduction.

According to the present invention, in another form thereof, the above mentioned comparison output is applied to the main oscillator of the tone generators thereby to obtain the desired equalization of pitches.

The nature, principles, details, and utility of the invention will be more clearly apparent from the following detailed description with respect'to preferred embodiments of the invention, when read in conjunction with the accompanying drawing, in which like parts-are designated by like reference numerals.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. I is a block diagram showing the essential organization of an example of an electronic musical instrument provided with a recorder-reproducer and one example of an automatic pitch synchronizing system according to the invention; and

FIG. 2 is a similar block diagram showing another example of embodiment of the invention.

DETAILED DESCRIPTION Referring to FIG. 1, the part of conventional organization of the electronic musical instrument shown therein comprises, in sequence, tone generators I, switches 2 operable by keys 3, filter circuits 4, tone volume controls 5, an amplifier 6, an expression control 7, a power amplifier circuit 8, and a loudspeaker 9.

In the example of the invention shown in FIG. 1, there is provided a recorder-reproducer 10 which is capable of recording simultaneously multichannel signals and reproducing the same and has a recording input terminal 101; and a reproducing output terminal l0ba corresponding to a specific track or channel and a recording input terminal and a reproducing output terminal 100a corresponding to a channel other than the first mentioned specific channel.

The recording input terminal 10a is connectable through a fixed contact 11f (recording) and movable contact 11m of a record-reproduce switch 11 to the junction between the ex pression control 7 and the power amplifier 8. The reproducing output terminal 10:14 is connected to the other (reproducing) fixed contact llfa of the switch 11. Thus, when the electronic musical instrument is played, the musical tone signals thus rendered can be recorded and subsequently reproduced by the recorder-reproducer I0. I

On the other hand, the recording input terminal 10b corresponding to the aforementioned specific channel is connectable through a fixed contact 12f (recording) and movable contact 12m of a switch 12 to a terminal 1a let out from a particular part of the tone generator circuit 1. Thus, when recording is carried out, a particular signal from the tone generator circuit is always recorded in the above mentioned specific channel.

In the instant example, there is further provided a detector circuit 14 having two input terminals 14a and Mara and being operable bytwo signals respectively supplied through these input terminals. The detector 14 thereupon operates to put out-an ambipolar DC voltage or current output proportional to the frequency difference of the two input signals, that is, a reference standard frequency minus the detected frequency, through an output terminal 14b.

One input terminal l4aa of the detector 14 is connectable through the movable contact 13m and fixed contacts 13f and l3fa of a switch 13 in a freely selectable manner to the input terminal 10b and output terminal l0ba of the recorderreproducer 10. The other input terminal 14a of the detector 14 is connected to the aforementioned terminal 1a of the tone generator circuit 1. The output terminal 14b is connected through a suitable power amplifier circuit I5 to an input terminal 100 of the driving mechanism of the recorderreproducer 10 together with a power supply 16 for the driving mechanism with a superimposed relationship thereto.

Although not absolutely necessary it is preferable that the above described switches 11, 12, and 13 be in mutually intercoupled or ganged relationship.

The example of the above described organization according to the invention operates in the following manner. First, the case where in a recording is to be made in the recorderreproducer will be considered.

In this case, movable contacts 11m, 12m, and 13m of switches ll, 12, and 13 are moved to the sides of their respective fixed contacts 11f, 12 and 13f. Accordingly, each musical signal is recorded in a channel other than the aforementioned specific channel. Simultaneously, a single signal among the signals generated in tone generator circuit 1, for example, A., 440 Hz, is obtained as a reference standard signal from terminal Ia and is recorded in the specific channel. It is to be observed that this signal is used as a control signal for controlling the reproducing speed of the recorder-reproducer at the time of reproduction as will become apparent as the description proceeds.

In this case, since the same signal A, 440 Hz is being supplied to both of the two input terminals 140 and Man: of detector 14, the frequency difference thereof is zero. Accordingly, the output at output terminal 14b of the detector is also zero, and the driving motor (not shown) of recorder-reproducer is driven by only power supply 16 for driving, no power whatsoever being supplied from power amplifier 15.

For reproduction, on the other hand, movable contacts 11m, 12m and 13m of switches 11, 12, and 13 are moved to the sides of their fixed contacts llfa, 12fa, and l3fa, whereupon each recorded musical signal is reproduced by recorderreproducer 10, amplified by power amplifier 8, and radiated as sound from loudspeaker 9. At the same time, the reference signal A, 440 Hz recorder in the-specific channel is also reproduced.

However, if at this time there is a pitch deviation due to causes such as deformation in the recording tape, fluctuation in the rotational speed of the tape drive motor, and fluctuation in the tone generators of the electronic musical instrument, the two signals applied to detector 14 as described'above differ from those at the time of recording.

For example, in the case when a stretching of the recording tape occurs, the signal from the tone generator circuit 1 corresponding to the recorded control signal has a frequency A, 440 Hz, but the reproduced signal from the above mentioned specific channel, i.e.,'the reproducing speed control signal, acquires a frequency which is lowered by the stretching of the tape. If, for example, this frequency is lowered to 435 Hz, the frequency difference between the tone generator signal and the reproduced speed control signal (detected signal) will become +5 Hz.

Accordingly, an output proportional to this frequency difference will be obtained at output terminal 14b ofdetector 14. This output will then be amplified by power amplifier 15 and, being superimposed on the output of power supply 16, will be supplied to the motor for driving recorder-reproducer 10. Thus, the power supplied to this motor will increase, whereby the motor speed will increase to increase the reproducing speed, and a musical reproduced signal of the correct pitch will be obtained.

Furthermore, in the case of pitch deviation due to a cause such as fluctuation in the tone generator circuit of the musical instrument as described above, wherein the frequency of the tone generator fluctuates to 435 Hz, for example, the frequency difference between this frequency and the reproduced speed control signal will become -5 Hz.

Accordingly, an output proportional to this frequency difference will be obtained at output terminal 14b ofdetector 14. This output will then be amplified by power amplifier 15 and be superimposed on the output of power supply 16. In this case, however, since the output of detector 14 is of negative polarity, the power supplied to the drive motor of recorderreproducer 10 will decrease, whereby the motor speed will be reduced, and control will be accomplished to equalize the pitch of the musical instrument and that of the musical reproduced signal.

In another example of practical embodiment of the invention as illustrated in FIG. 2, the known organization of the electronic musical instrument proper comprising tone generators 1, switches 2 operable by keys 3, filter circuits 4, tone volume controls 5, an amplifier 6, an expression control 7, a power amplifier 8, and a loudspeaker 9 is similar to that of the example described hereinabove with reference to FIG. 1.

Furthermore, a multichannel recorder-reproducer 10 of magnetic type capable of simultaneous recording and reproducing multichannel signals and a comparison detection circuit or detector 14 are also connected to the musical instrument proper in a manner similar to that in the example shown in FIG. 1 except that the output terminal 14b of the detector 14 is connected to a frequency control terminal lb of a main oscillator within the tone generator circuit 1 thereby to control the oscillation frequency thereof. The. detector gives out a control signal proportional to the frequencyrdifference of the detected frequency minus the main oscillator frequency.

The components of the circuit including switches 11, 12, and 13 and their connections are the sarneas those in the example shown in FIG. 1. Y

For recording, movable contacts l1m,.l:2m and 13m of the three switches are moved to engage respectively fixed contacts 11f, 12f, and 13f, whereupon eachflmusical tone signal which has passed through expression control 7 is supplied through movable contact 11m and fixed contact 11f and through input terminal 10a to recorder-reproducer 10 to be recorded in a channel other than the aforementioned specific channel.

At the same time, one signal from among the tone generator signals generated and transmitted through output terminal la of tone generators l, for example, a signal A 440 Hz, is led out as a reference standard signal. This signal is supplied by way of movable contact 12m and fixed contact 12f and through input terminal 10b to recorder-reproducer 10 to be recorded inthe above mentioned specific channel.

In this case, since the two input signals with'respect to the detector are both signals of A 440 Hz, the frequency difference is zero, and, therefore, the detector output is also zero. Accordingly/since no signal whatsoever is supplied to the main oscillator ofthe tone generators 1, there is no variation in the oscillation frequency.

For reproducing, switches ll, 12, and 13 are changed over by placing movable contacts 11m, 12m and 13m in contact with fixed contacts llfa, l2fa, and 13fa Each musical tone signal recorded in recorder-'reproducer 10 is reproduced and, passing through fixed contact 11 fa and movable contact 11m of switch 11, is power amplified by power amplifier 8 and radiated as sound from loudspeaker 9. Simultaneously, the reference standard signal A, 440 Hz of tone generators 1 recorded in the specific channel is also reproduced.

However, if at this time there is a pitch deviation due to any of the aforementioned causes, the two signals applied to detector 14 will differ from those at the time of recording. For example, in the case when a stretch occurs in the recording tape, the signal from the tone generators is A4 440 Hz, and if the signal reproduced from the recorder-reproducer becomes of a frequency of 435 Hz, for example, because of the stretch in the tape, the frequency difference between the detected signal and the tone generator signal will become 5 Hz.

Consequently, the output of detector 14 will become proportional to this frequency difference. This output is then applied to the main oscillator of tone generators l to effect control whereby the oscillation frequency thereof is reduced, thereby operating to cause the reproduced musical tone signal from the recorder-reproducer and the signal of the tone generator of the electronic musical instrument to become equal in pitch.

Furthermore, in the case wherein the pitch ofa tone generator of the musical instrument deviates from the standard pitch, resulting with the detector input from the tone generator being at a frequency of 435 Hz, and the reproduced reference signal from the recorder-reproducer is normally of a frequency of 440 Hz, for example, the frequency difference between the reproduced reference signal and the tone generator signal will be +5 Hz. Since the output of detector 14 is proportional to this difference, a signal such as to raise the oscillation frequency is applied to the main oscillator of the tone generators 1, whereby the pitch of the musical tone reproduced signal of recorder-reproducer 10 and the pitch of the tone generator of the musical instrument are caused to be equal.

In the first described example of the invention, the operation comprises, essentially, recording simultaneously musical tone signals and one signal within the same tone generator as a reference signal at the time of recording, comparing this reference signal at the time of reproduction with the corresponding tone generator signal of the electronic musical instrument, and applying the resulting comparison output to the driving motor of the recorder-reproducer thereby to obtain musical tone signal of the same pitches as the corresponding pitches of the musical instrument played at the time of reproduction.

In the second example of the invention, the operation comprises, essentially, recording simultaneously a musical tone signal and one signal within the same tone generator as a reference signal at the time of recording, comparing this signal with the corresponding tone generator signal of the musical instrument at the time of reproduction, and applying the resulting comparison output to the main oscillator of the tone generators thereby to cause the pitch of each reproduced musical tone signal and thepitch of the corresponding tone of the electronic musical instrument to be equal,

Thus, an electronic musicalinstrument provided with an incorporated sound recording and reproducing apparatus and with the pitch synchronizing system of the invention is capable of rendering superimposed tones and chords in an extremely beautiful manner in instances such as, for example, that of a duet rendered by playing the musical instrument in concert with a reproduced musical composition or that wherein use is made of a recording tape with sound recorded thereon for purposes such as practice in playing the electronic musical instrument. I

While, in each of the above described examples of the invention, a tone generator tone signal of the electronic musical instrument itself is used as a reference signal, it will be apparent that a separate signal source can also be used.

It should be understood, of course, that the foregoing disclosure relates to only preferred embodiments of the invention and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention as set forth in the appended claims.

lclaim:

l. in an electronic musical instrument having tone generators, a loudspeaker, and a magnetic sound recording and reproducing apparatus driven by motive power means and incorporated within the instrument for recording and reproducing musical tone signals played thereon, an automatic pitch synchronizing system comprising, in combination:

means for recording and reproducing a reference signal simultaneously with and separate from said musical tone signals; detectionmeans for comparing, during reproduction, the reference signal thus reproduced with a respective signal directly from the corresponding tone generator to produce a comparison signal which is a function of the difference between the signals thus compared; and control means operating in response to said comparison signal to equalize, during reproduction, the pitches of the reproduced musical tone signals and the pitches of corresponding tones played on the instrument during said reproduction. 2. The automatic pitch synchronizing system as claimed in claim 1 in which the control means operates in response to the comparison signal to control said motive power means thereby to control the reproduction speed of the recording and reproducing apparatus.

3. The automatic pitch synchronizing system as claimed in claim 1 which further comprises a main oscillator of variable frequency for the tone generators, and in which the control means operates in response to the comparison signal to control the oscillation frequency of said main oscillator.

4; The automatic pitch synchronizing system as claimed in claim 1 in which the detection means is a detector circuit having an input terminal connected to an output terminal of the tone generators, and the means for recording and reproducing a reference signal com rises the ma netic sound recording and reproducing appara us, which is 0 multiple channel type having a specific channel for recording the reference signal, and switching means for directing the reference signal from a tone generator directly as input to said specific channel during recording and for directing the recorded reference signal from the specific channel to another input terminal of the detector circuit during reproduction. 

